Polymer particles with additives encapsulated in microvoids

Abstract

Porous particles comprising a polymer binder and at least one additive distinct from any pore stabilizing compound present in the particle, wherein: the polymer binder comprises a solid compositionally continuous phase having an external particle surface; discrete pores are dispersed within the solid compositionally continuous phase, forming internal pore surfaces; and the at least one additive is present primarily in the discrete pores. The additive may further preferably not be present in the solid compositionally continuous phase, and be substantially absent from the external particle surface. A toner set for forming a color electrophotographic image comprising a plurality of different colored toners, where at least one of the different colored toners comprise such porous particles comprising additives, and in a particular embodiment wherein at least two different colored toners each comprise different pigments present primarily in the internal pores. A process of making such porous particles.

1. A porous particle comprising a polymer binder and at least one additive distinct from any pore stabilizing compound present in the porous particle, wherein:
 the polymer binder comprises a solid compositionally continuous phase having an external particle surface; 
 discrete pores are dispersed within the solid compositionally continuous phase, forming internal pore surfaces; and 
 the at least one additive is present primarily in the discrete pores. 
 
     
     
       2. The porous particle of  claim 1 , wherein the at least one additive is not present in the solid compositionally continuous phase or on the external particle surface. 
     
     
       3. The porous particle of  claim 1 , wherein the at least one additive comprises at least one of a colorant, a release agent, a magnetic particle, a matting agent, or a biologically active agent. 
     
     
       4. The porous particle of  claim 1 , wherein the at least one additive comprises a colorant. 
     
     
       5. The porous particle of  claim 4 , wherein the colorant comprises a pigment. 
     
     
       6. The porous particle of  claim 1 , wherein the at least one additive comprises a wax. 
     
     
       7. The porous particle of  claim 1 , wherein the at least one additive comprises magnetic particles. 
     
     
       8. The porous particle of  claim 1 , further comprising a pore stabilizing hydrophilic colloid. 
     
     
       9. The porous particle of  claim 1 , wherein the porous particle has a porosity of at least 10 percent. 
     
     
       10. The porous particle of  claim 1 , wherein the porous particle is nonspherical. 
     
     
       11. A toner set for forming a color electrophotographic image comprising a plurality of different colored toners, where at least one of the plurality of different colored toners comprises porous particles according to  claim 1 . 
     
     
       12. The toner set according to  claim 11 , where at least two of the different colored toners comprise porous particles according to  claim 1 . 
     
     
       13. The toner set according to  claim 12 , wherein the at least two of the different colored toners each comprise different pigments present primarily in the discrete pores of the porous particles. 
     
     
       14. The toner set according to  claim 13 , wherein the at least two different colored toners comprise at least two of cyan, magenta, yellow, and black toners. 
     
     
       15. A method of making porous particles comprising a polymer binder and at least one additive, comprising:
 providing a first aqueous phase comprising at least one additive; 
 dispersing the first aqueous phase in an organic solution containing a polymer binder to form a first emulsion; 
 dispersing the first emulsion in a second aqueous phase to form a second emulsion; 
 shearing the second emulsion in the presence of a particulate stabilizing agent to form droplets of the first emulsion in the second aqueous phase; and 
 evaporating the organic solution from the droplets to form porous polymer particles; wherein: the formed polymer porous particles comprise a solid compositionally continuous polymer binder phase having an external particle surface; discrete pores are dispersed within the solid compositionally continuous polymer binder phase, forming internal pore surfaces; and the at least one additive is distinct from any pore stabilizing compound present in the porous particle and is present primarily in the discrete pores. 
 
     
     
       16. The method of making porous particles according to  claim 15 , wherein the first aqueous phase further comprises a pore stabilizing hydrocolloid. 
     
     
       17. The method according to  claim 15 , wherein the at least one additive comprises at least one of a colorant, a release agent, a magnetic particle, or a matting agent. 
     
     
       18. The method according to  claim 15 , wherein the at least one additive comprises a colorant. 
     
     
       19. The method according to  claim 15 , wherein the at least one additive comprises a wax. 
     
     
       20. The method according to  claim 15 , wherein the porous particle has a porosity of at least 10 percent.